The example in the slideshow is an 1100W microwave but you did your math with a 1000W microwave. I know its only 100w difference but an error like that is extremely important for people who are doing this following along to the video. Be cautious of this mistake in the math, because i spent quite some time trying to figure out why i kept coming up 100W too high when my math was actually correct
The way I read 220.82(C)(3) is that if you have a heat pump with a furnace, you would use 100% of the heat pump AND (code uses word AND) 65%% of the supplemental furnace heat. In this very common residential case, it is not heat OR A/C, It is A/C heat pump at 100% PLUS furnace heat at 65% as one of the choices in (C) Am I reading this wrong? All RU-vidrs seem to be sticking with heat OR A/C, not considering (C)(3).
The purpose of the video is to prepare folks that are taking the exam. The vast majority of exams don’t take into account the common real world scenario of having supplemental heat. This is the reason that I did not include that information in the video.
The 65% percent rule is under 220.82 which is for SINGLE family dwellings. For multi-family you compare the larger of 100% of air conditioning and 100% of the heat according to 220.84(C)(5).
Thank you for the video. Clarified a lot of things for me. For the General Loads, the NEC says at least 2 circuits at 1500ea for appliances and 1 for Laundry, is there ever a situation where you use more than just 2 small appliance and 1 laundry?
2 small appliance circuits is the minimum. You are free to add any additional small appliance circuits as well for additional equipment/receptacles. If you add additional, just use 1500 for each.
@@opecons I guess you would have to calculate using the standard method first to determine whether the optional method could be used. I have never considered that. That seems like a pain.
4kw is correct because we are using the optional method. One of the most common errors in calculating using the optional method is using rules from the standard method. The 5kw rule is used only when calculating the standard method.
also, i have my exam coming up soon, how will i know if the optional method would be sufficient for an answer instead of the standard method? im going for SFD.@@constructionseminars4197
Would you add the EV charger into this at 100% of the rated VA, and not add it into the appliances? If added in the appliances we’d effectively be reducing the rating of the EV by 40%.
Although not specifically spelled out in the optional method calculations, I believe that an electric vehicle charging station would meet the definition of an appliance, and would be included in that load.
Interestingly I had an inspection this morning and asked the inspector the same question. He said I should not treat it like an appliance and use its rated VA at 100%. In my load calc I added that to the VA after the 40%. He said that was what he would want to see moving forward.
I think the calculation is wrong. Adding all the load for individual should be 36,100 instead of 34,600. If you multiply by 10 unit that would be a big error.
Yes, you are correct. 36,100 x 10 = 361,000. 361,000 x 43% = 155,230. 155,230/240 = 646.79 amperes. That would still require 700A service so the final answer on a test would be the same. Sorry about the mistake, looks like you are the first one to catch it. Good job. Hopefully the math concepts and steps still communicate well.
